Screw propeller



Dec. 27, 1932.

E. A. L. THAY ER SCREW PROPELLEB Filed April 30, 1931 Patented; Dec. '27, 1932 .UNITED STATES PATENT OFFICE.

EDWARD A. L. THAYEB, OF CHICAGO, ILLINOIS SCREW PROPELILER Application filed April 30, 1931. Serial No. 588,962.

This invention relates to a screw propeller and has special referenceto a screw propeller of the type for use in conjunction with marine and aerial navigating vessels.

More particularly, this invention relates to ascrew propeller stantially helicoidal blades each of which preferably makes practically a complete convolution around the stem or hub thereof, the front and rear portions of the blade being -concavo-convex when viewed in cross-section.

asthe propeller revolves will tend to be directed backwardly and toward the hub to obviate 'the tendency usual in propellers as hitherto generally constructed to carry the water around with the blades and by which the liquid will be directed with a. minimum resistance to the center of the propeller. Such a propeller would act with a maximum eflic'iency of propulsion and would produce a minimum of commotion in the water. Y

The dished front portion of the convolution forming the blade cuts into the water or other fluid so as to afford the least resistance in entering and directs the fluid into the central portion of the propeller to be acted upon by the oppositely dished rear portion of the convolution forming the blade, the liquid being directed centrally rearward to increase the effect of propulsion as though the propeller were acting on-a .solid mass. The outer ends of the blade being formed with aving one or more sub in proportion to the length thereof. The width of the blades is, of course, reduced in proportion to the number thereof. It has been found that in using two blades each of the hub, the largest diameter of the blades should be approximately equal to or not substantially greater than the length thereof. The blade is gradually narrowed in width in which makes a complete convolution around 5 both directions from an enlarged substantially central portion and the blades are bowed backward a little instead of being perpendicular to the hub from the enlarged portion of the convolution to the rear end thereof to produce a tendency in the fluid which they 6 drive backward to converge to a point. It is assumed that this convergent tendency may balance the divergent tendency due to the centrifugal force attending the revolution so that the two forces being in equilibrium will cause the fluid to be projected backward from the screw in a cylindrical column. The blades are bowed forward a little from the enlarged portion on the convolution noted above to the leading end thereof to cut into the fluid so as to aflord'the least resistance in entering and to direct the fluid into the propeller instead of deflecting the same therefrom.

The provision of an entire convolution on the hub gives a maximum area of propelling surface with a minimum width of blade thereby requiring a minimum of thrust or force exerted on the a pair of blades having so shaft to propel the vessel. By reason of the comparatively small width of blade at the forward end thereof and the dished or inclined condition of the blade thereat, the entire propeller is live and practically devoid of fluid drag blades. e

One of the objects of this invention is to v provide a propeller-of the type noted above in which the blade makes a,complete convolution around the hub, the front end thereof 9 being inclined forwardly and the rear end being inclined rearwardly to afford a maximum efiiciency of propulsion Another object of this invention is to provide a propeller of the character noted above between convolution of the 9 in which the leading end of the blade graducident to the propeller in case of collision with projecting solids.

Other objects and advantages will hereinafter be more fully pointed out and for a more complete understanding of the characteristic features of this invention reference may now be had to the following description when read together with the accompanying drawing, in which latter:

Figure 1 is a side elevational view of the propeller embodying the features of this in vention; V p 7 i Fig. 2 is a front elevational view of Figure Fig. 3 is a vertical sectional view of a blade showing a portion of the hub taken on the line 3-3 of Figure 1;

Fi 4 is a' view similar to Fig. 3 taken on the l1ne 4-4: of Figure 1; and

Fig. 5 is a view similar to Fig. 3 taken on the 11119 5-5 of Figure 1.

Referring now -more particularly to the drawing, the device of this inventlon comprises a propeller hub or stem 10 having a central bore 11 for ixeceivin a power shaft of a vessel. A pair of substantially helicoidal blades 12 and 13. extend from the hub,

each blade preferably making practically a complete convolution therearound.

The dynamic pressure of the reaction developed between the water and the helicoidal surfaces of the blades when revolved in one direction drives the vessel forward and to insure a maximum efliciency of propulsion, each blade is bowed in a direction toward the rear from a substantially central portion of the is shown to be bowed in the opposite direction to that of the rear end of the blade. It is contended that this shape permits the entrance of the propeller into the liquid with the least commotion thereto, the blade cutting into the liquid as an anger into a solid. This easy entrance of the water into the propeller prevents churning to a substantial degree,

which latter would result in a substantial ineasure were the blade disposed perpendicuarly thereto. After the liquid is in the'screw with the respective concave and convex to the hub or at a rearward inclination,

tween the liquid and the rearwardly bowed helicoidal surfaces takes above described.

It will also be noted that the leading end of the blade tapers in width gradually from the hub to an enlarged portion substantially centrally of the length thereof. By referring to Fig. 2 of the drawing, it will be seen that there is very little overlapping of-the blades and that in practical effect, there is no drag and every portion of the blade is put to work. Also, by reason of this gradual taper from a central portion to each end there is little likelihood of the blades catching in weeds or bumping into logs and the like. It is a common occurrence for a blade of the usual type to be broken from the shaft by striking a projecting solid member. In the instant a plcation, a projecting member would given a glancing blow in any event and there place in the manner would be no danger of fracturing or breaking the blade. There are no sharp edges to catch weeds or refuse and therefore the pro peller may be said to be Weedless. I

While but a single embodiment of this invention is herein shown and described, it is to be understood that various modifications may be apparent to those skilled in the art without departing from the spirit and scope of this invention and, therefore, the same is to be limited only by the scope of the prior art and the appended claims.

I claim:

1. A screw propeller comprising a hub for engagin a power shaft, anda .pluraht of substantially helicoidal blades on said ub, the front and rear portions of each of said blades being concavo-convex when viewed in cross-section with the convex faces facing each other and the respective concave an convex'faces mer ing in a substantially flat -surface between t e ends of said blades.

2. A screw propeller comprising a. hub for engaging a power shaft, an at least one sub stantially helicoidal blade forming practically a completeconvolution on said hub, the front and rear portions of said blade being bowed in directions away from each other."

'3. A screw propeller comprising a hub for engaging a power shaft, and at least one substant ally helicoidal blade formin practically a complete convolution on sai hub, the

front and rear portions of said blade being concave-convex when viewed in cross-section with the convex faces facing each otherf and aces mergin in a substantiall flat surface between t e ends of said'bla e.

4. A screw propeller comprising a hub for engaging a power shaft, and a plurality of substantially helicoidal blades each of which forms practically acom lete convolution on said hub, said blades ing gradualalf reduced in width from an enlarged cent-r tion to the hub and having the front and rear portions of each of said blades bowed in opposite directions.

5. A screw propeller comprising a hub for engaging a power shaft, and at least vone substantially helicoidal blade forming practically a complete convolution'on said hub, said blade being radually reduced in width from an enlarged central ortion to the hub and having the front an rear portions of said blade bowed in directions away from each other.

6. A screw propeller comprisin a hub for engaging a power shaft, and a su stantially helicoidal blade on said hub, the front and rear portions of said blade being concavoconvexwhen viewed in cross-section with the convex faces facing each other and the respective concave and convex faces merging in a substantially flat surface between the ends of said blades.

In witness whereof, I have hereunto subscribed my name. EDWARD A. L. THAYER. 

